[Assessment of the use of various cardiac pacing modes for selection of antiarrhythmic therapy for prevention of recurrent attacks of atrial fibrillation and flutter]. / Otsenka ispol'zovaniia razlichnykh rezhimov kardiostimuliatsii dlia opredeleniia protivoretsidivnoi antiaritmicheskoi terapii paroksizmov mertsaniia i trepetaniia predserdii

AIM: To determine optimal mode of transesophageal pacing for selection of appropriate antiarrhythmic therapy for prevention of attacks of atrial fibrillation and flutter in patients with ischemic heart disease. MATERIAL AND METHODS: Two hundred eighteen patients with ischemic heart disease and attacks of atrial fibrillation or flutter. Selection of antiarrhythmic drugs was carried out with the use of competitive, rapid, salvos of ultra rapid, and slowly accelerating ultra rapid modes of pacing. Results. Most effective and reproducible method for induction of attacks of atrial flutter and fibrillation was slowly accelerating ultra rapid mode of pacing. Average duration of positive clinical effect of preventive antiarrhythmic therapy selected basing on the results of this mode in patients with ischemic heart disease was 3.1-/+0.3 years. Unfavorable prognostic sign decreasing preventive effect of antiarrhythmic therapy was left atrial dilatation. CONCLUSION: Slowly accelerating mode of transesophageal pacing was most effective tool for selection of antiarrhythmic therapy aimed at prevention of attacks of atrial fibrillation and flutter in patients with ischemic heart disease.

[A new multipolar transesophageal electrode for assessment of activation sequence in the left atrium]. / Nowa, wielobiegunowa elektroda przelykowa do badania sekwencji pobudzenia lewego przedsionka.

A new multipolar transoesophageal electrode is described. Two patients were analysed. One with recurrent coronary sinus rhythm and the other with concealed WPW syndrome. Obtained recordings showed difference of sequence of left atrial depolarisation during recovery of the sinus rhythm after its overdrive suppression and during provoked tachycardia. Results are very promising and require further investigation.

Clinical assessment of respiratory sinus arrhythmia by computerized analysis of RR interval and respiration.

Heart rate variability (HRV) and respiratory sinus arrhythmia (RSA) are often considered as interchangeable terms. However, the application of power spectral analysis to describe spontaneous fluctuations in heart period has clearly shown that RSA is only a part of HRV, and that in specific situations their respective patterns may diverge. In order to quantify the RSA we have used a mathematical method based on combined spectral analysis of respiration and RR interval (cross-correlation function), and evaluated its performance in terms of reproducibility, sensitivity to parasympathetic withdrawal and in clinical evaluation of autonomic function. Compared to other indices of HRV the cross-correlation between RR interval and respiration showed a greater sensitivity to parasympathetic withdrawal, better reproducibility and a high sensitivity in detecting autonomic dysfunction in diabetic patients. These findings suggest that specific indices of RSA, such as the cross-correlation, can be a valid tool for the diagnostic approach to cardiac autonomic dysfunction.

A computerized respiratory sinus arrhythmia program for the non-invasive assessment of parasympathetic activity.

The availability of sophisticated signal analysis methods based on the use of micro-computers allows an accurate non-invasive assessment of parasympathetic activity, through the measurement of the respiratory sinus arrhythmia. The program described herein is in Quickbasic and consists of 5 programs. At termination of the computer analysis the results are printed which include the average heart rate for inspiration and expiration, the averaged standard deviation of the R-R intervals for inspiration and expiration, and the R-R interval in milliseconds averaged for all inspiratory and expiratory cycles. Significant correlations were obtained when comparing the analyses of the computerized program with a manual method.

An improved method for measuring heart-rate variability: assessment of cardiac autonomic function.

Heart rate oscillates in synchrony with respiration. Several methods have been employed to assess this 'sinus arrhythmia', as an index of autonomic nervous system function. This paper proposes a new, easily computed measure, R, which is relatively resistant to the major nonrespiratory sources of variation, including premature beats, heart-rate differences among subjects, and slow trends in heart rate over time within subjects. The method can also be used more generally in any context where individuals are associated with event processes (for example, with seizures), when one requires assessment of the extent to which a point process is periodic with a particular known period.

Autonomous influence on sinus node and AV node function in the elderly without significant heart disease: assessment with electrophysiological and autonomic tests.

Eighteen volunteers with a mean age of 63.3 years, who were asymptomatic and without significant heart disease, were investigated with standard electrophysiological tests, performed before and after inhibition of autonomous neural tone with propranolol (0.1 mg . kg-1) and atropine (0.02 mg . kg-1). In addition heart rate responses to maximal exercise, carotid sinus pressure and bolus injection of isoprenaline (0.01 microgram . kg-1) were studied to evaluate the relation between different functional qualities of the cardiac conduction system. Autonomous tone inhibition (ATI) caused significant reductions in the mean PP-interval, sinus code recovery time (SNRT) and corrected sinus node recovery time (CSNRT). Furthermore, the precision of CSNRT determinations increased after ATI. In contrast, the AV-node effective refractory period and conduction time (AH-interval) did not change after ATI. A significant correlation existed between CSNRT and heart rate after ATI, both variables reflecting sinus node automaticity, while no covariation was found between CSNRT and the response to isoprenaline stimulation. AV-node refractoriness and conduction time showed covariation after, but not before, autonomous inhibition. As elderly asymptomatic non-patients were examined the use of the presented group characteristics as reference values for diagnostic investigations is suggested. For example pre-drug CSNRT above 545 ms (mean + 2 SD) or above 505 ms after ATI, indicates impaired sinus node automaticity.